GB2166048A - Means for engaging chair with walking aid - Google Patents

Abstract

A chair has a powered mechanism for raising and lowering the seat, the seat controlling a linkage 33, (34) so that the first position of the seat raising movement additionally causes a latch 40 in the front part of the chair to lower until a stop 39 is engaged with arm 33, after which further raising of the seat will not lower the latch any further. The stop 39 may be set such that the latch 40 at the corresponding position is easily engageable with a releasable gate mechanism 41 incorporated on a swivel walker 42 or other device. The chair may be a folding wheel chair. <IMAGE>

Description

SPECIFICATION Docking mechanism for walking aid This invention relates to aids for the disabled, and in particular provides a mechanism to enable users to become more mobile and to make greater use of other devices available.

It is widely believed that many, if not most, paraplegic patients benefit physically, as well as psychologically, from spells of activity in which they are in the upright position: the risks of pressure sores may be reduced and bladder drainage and pulmonary function may, for example, be improved over that resulting from spending long continuous spells in bed or wheelchair.

One of the devices developed to combine a support for patients in the upright position with a certain degree of mobility is the socalled swivel walker, in the conventional type of which the patient is retained against a rigid frame. By a combination of alternating leaning and twisting he achieves movement by the particular arrangement of shape, hinges and bearings at the lower end of the swivel walker. Originally, the design of swivel walkers was such that the patient had to be placed into the device rearmost first before retaining straps could be inserted across the patient's front; except with small children, these were awkward to don and dock and therefore relatively unpopular with users. More recently, an improved walker has been developed into which the patient enters from the rear; this is described in J. Biomed. Eng, Vol 4, 325-7.

The rigid uprights of the walker are hinged at the hip and knee so that the patient may don the walker when sitting in a chair; without further assistance however, the patient is unlikely to be able to lift himself from the chair into the upright position. The present invention is intended to provide means for releasably attaching the chair to a rear-entry swivel walker and means for lifting the patient, having donned the walker, into the upright position and vice versa. The chair may be a wheelchair or a static one, with or without castors.

This invention accordingly consists of a chair adapted to dock with an aid for upright stance, comprising a rigid frame, a seat assembly pivotally mounted on the frame, means for raising and lowering the seat assembly, a docking mechanism engageable with the said aid, and means linked with the seat assembly for raising and lowering said docking mechanism whereby the docking mechanism is lowered by at least part of the raising movement of the seat assembly and vice versa.

Conveniently there may be provided two similar docking mechanisms one extending forward from each of the side frames of the chair, each docking mechanism being engageable with the aid, for example, with a respective upright of a swivel walker.

The docking mechanism may include a horizontal stud engageable with the aid in the manner of a latch when moved forward at the correct height, into a gate incorporated in the aid and operable by the patient to separate the docked members.

The means for raising and lowering the docking mechanism may comprise a linkage including two arms each pivoted to both the docking mechanism and the rigid frame of the chair whereby rotation of the arms causes an upward or downward translation of the docking mechanism, one of said arms extending rearwardly of its pivot on the rigid frame, said extension being urged upwards against a part of the seat assembly whereby upward movement of the seat assembly results in rotation of said arms and a corresponding downward movement of said docking assembly.

The linkage may include means for preventing downward movement of the docking mechanism below the height range in which engagement with the swivel walker is readily achieved, even though the seat may continue to be raised.

By way of example, one embodiment of the invention will now be described with reference to the drawings, of which Figure 1 is a side elevation of a wheelchair incorporating an attachment for docking with a rear-entry swivel walker; Figure 2 is a part rear elevation of the wheelchair illustrated in Fig. 1, and Figure 3 is a sketch illustrating the invention in use.

With reference to Fig. 1, a wheelchair comprises a rigid alloy frame 1 on each side of the wheelchair (only the right-hand frame being shown in Fig. 1), the frames 1 each supporting in bearings 2 a front castor wheel 3 and in bearings 4 (see Fig. 2) one of the main, rear wheels 5.

The frames 1 are interconnected by crossshafts 6, 7 and 8 incorporating respectably lockable hinges 9 and 10 disposed one on either side of the centre line or a central hinge 11. Tie-bars 1 2 extend from pivots 13 on the rigid frame to either side of the central portion of the shaft 6 in order to relieve the shaft of excessive stress when the wheelchair seat is in a raised position.

The seat 14, constructed in two parts connected by hinge 15, extends between two generally horizontal tubular members 16 one on each side of the wheelchair. The members 1 6 are attached at their forward end by a pivot 17 to a forwardly extending part of the frame 1. At the rear end, they are each attached by a pivot 18 to a tubular member 19 which extends upwardly to form a handle 20 for the wheelchair and which provides support for a battery box 21, a back rest 45 and an arm rest 22 which may be swung upwards on pivot 23. The member 19 extends down wards beyond the pivot 18 to a pivot 24, by which it is connected to a further member 25 which itself is connected to frame 1 by pivot 26 located close to pivot 17 in such a way that pivots 17, 18, 24 and 26 form a parallelogram.Thus, as seat 14 is raised, then members 16 and 25 remain generally parallel and the back member 19 and its associated components remain in the same attitude. When the seat 14 is in the normal (horizontal) position, the weight of the upperpart of the chair is borne by the frame 1 through two resilient rests 27 and 28 affixed to the frame 1 and into which the members 19 and 16 respectively engage.

The seat is pivotted upwards about the pivot 17 by operation of a screw-type electrical actuator 29 actuated by electric motor 30 powered by a set of rechargeable Ni/Cad batteries located in the battery box 21 and controlled by a switch 31 located at the end of one of the arms 22. The actuator 29 extends from the mid-point of the shaft 6 to a bearing 46 located on the centre line of the seat 14.

The docking mechanism consists of a plate 32 pivotally attached to two arms 33, 34, the arms in turn being pivotally attached by pivots 35, 36 respectively to a forward part of the frame 1. The arm 33 extends rearwardly beyond pivot 35 and supports at its rear end a rolier bearing 37 engageable with the lower surface of the tubular member 16. A tension spring 38 extends between the frame 1 and the lower arm 34 so that as the seat 14 is raised, the arms 33, 34 rotate under the action of spring 38 as the roller bearing 37 remains in contact with the member 16.The pivots at the end of the arms 33, 34 are arranged approximately as a parallelogram; as the seat 14 continues to be raised, the arms 33, 34 get closer to one another until a stop 39 fixed to the lower arm 34 and engageable with arm 33 prevents further rotation of the arms so that as the seat 40 is raised further, no further rotation of the arms, and hence lowering of the plate 32, takes piace. At the forward end of the plate 32, there is provided an inwardly extending stud 40 which is engageable with a gate 41 (Fig. 3) fixed on an upright member of the swivel walker 42. An L-shaped member 43 adjustably screwed to the plate 32 is arranged to abut the upright of the swivel walker when the stub 40 is engaged to prevent forward rotation of the swivel walker away from the patient.The position of the stop 39 is adjusted so that when the stop 39 engages with the arm 33, the stub 40 is at a height off the ground at which it will readily engage with the gate 41.

In operation, the patient manoeuvres the wheelchair into a position in which the studs 40 are in line with and just above the gates 41. By actuation of the motor 30, he will then raise the seat slightly until the stop 39 engages with arm 33 whereupon he can move the wheelchair forwards and engage both stubs 40 with their respective gates 41. At this stage, the patient can release the hinges on the swivel walker so that it can be folded around the body and hence make it easier for him to attach himself to the upper portion of the walker; he can then either lower the wheelchair seat again to raise plate 32 and hence be able to move away taking the swivel walker with him, or else raise the seat to its maximum extent so that he is standing vertically upright and able to lock the swivel walker in its normal operating condition.This is made easier by his being able to gain support from the arms 22 which have remained in a near-horizontal attitude even though the seat has rotated. Once he has satisfied himself that he is secure in the swivel walker, he can release the gates 41 by cords located at a convenient position and walk away from the wheelchair. By reversing this procedure, he may readily sit down again in the wheelchair.

For storage, for example in a car boot, the wheelchair may be folded. This may be achieved by firstly removing the seat cushion 44, releasably attached to the seat 14, and the backrest 45, which is a sliding fit between members 19. A hand knob (not shown) may then be released to enable the seat 14 to fold along the hinge 15, and hinges 9, 10 on shafts 6 and 7 can be released. As the seat is pulled from above into the folded position, the side members then move towards one another. This procedure is reversed to unfold the wheelchair.

Although the invention has been described with reference to a drawing of a wheelchair adapted for use with a swivel walker, it will be readily apparent that the invention will be applicable to many other aids for the disabled where it is desirable for the patient to raise himself into the upright position against the aid where hitherto there have been problems in coupling the wheelchair and the aid. It will also be apparent that the mechanism could equally effectively be incorporated into the design of a conventional legged chair having suitable rigid frames and a seat which can be hinged in the way illustrated above in the case of a wheelchair.

Claims (5)

1. A chair adapted to dock with an aid for upright stance, comprising a rigid frame, a seat assembly pivotally mounted on the frame, means for raising and lowering the seat assembly, a docking mechanism engageable with the said aid, and means linked with the seat assembly for raising and lowering said docking mechanism whereby the docking mechanism is lowered by at least part of the raising movement of the seat assembly and vice versa.

2. A chair according to Claim 1 in which the docking mechanism includes a horizontal stud engageable with the aid in the manner of a latch when moved forward at the correct height into a gate incorporated in the aid and operable by the patient to separate the docked members

3. A chair according to either preceding Claim in which the means for raising and lowering the docking mechanism comprises a linkage including two arms each pivoted to both the docking mechanism and the rigid frame of the chair whereby rotation of the arms causes an upward or downward translation of the docking mechanism, one of said arms extending rearwardly of its pivot on the rigid frame, said extension being urged upwards against a part of the seat assembly whereby upward movement of the seat assembly results in rotation of said arms and a corresponding downward movement of said docking assembly.

4. A chair according to Claim 3 in which the linkage includes means for preventing downward movement of the docking mechanism below the height range in which engagement with the swivel walker is readily achieved, even though the seat may continue to be raised.

5. A wheelchair incorporating means for docking with a swivel walker, substantially as hereinbefore described with reference to the drawings.